摘要
分别以Na_2CO_3和NH_3·H_2O为沉淀剂和络合剂,用共沉淀法和950℃高温烧结制备Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2,并用湿化学法将LaF_3包覆在Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2正极材料表层。用XRD,SEM,TEM等手段表征了LaF_3包覆前后Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2颗粒的微观结构和表面形貌,用电化学测试仪检测样品的充放电性能。结果表明,包覆前后材料的结构没有变化,已经成功地将LaF_3包覆在Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2表面;LaF_3包覆使Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2的电化学综合性能明显提高。在5C高倍率下,LaF_3-Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2的放电比容量比原始Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2超过了20.3 mAh·g^(-1)。经过100次循环后LaF_3-Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2的容量保持率高达94.8%,循环稳定性更佳。这些结果表明,LaF_3包覆改性是提高Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2电化学性能切实可行的方法。
Cathode material of Li[Li0.2Mn0.54Ni0.13Co0.13]O2 was synthesized firstly via co-precipitation method with Na2CO3 and NH3.H2O as precipitation agent and complexing agent respectively and then fol- lowed by high temperature sintering process at 950℃. Further, the prepared Li[Li0.2Mn0.54Ni0.13Co0.13]O2 was coated with LaF3 through wet chemistry method. The Li[Li0.2Mn0.54Ni0.13Co0.13]O2 without and with LaF3 coating was characterized by means of XRD, SEM, TEM. The results show that the Cathode material may be successfully coated with LaF3 without changing its microstructure. Finally, the cathode material was examined by electrochemical means and which shows that its electrochemical properties were signif- icantly enhanced after applying the LaF3 coating. The specific discharge capacity of the LaF3 coated Li Li[Li0.2Mn0.54Ni0.13Co0.13]O2 is 20.3 mAh.g-1 higher than that of bare Li[Li0.2Mn0.54Ni0.13Co0.13]O2 at 5C rate. Mean- while, the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 delivered an outstanding cycle stability with a high capacity reten- tion of 94.8% after 100 cycles. Therefore, LaF3 coating method could be an effective way to enhance the electrochemical properties of Li[Li0.2Mn0.54Ni0.13Co0.13]O2.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2017年第5期394-400,共7页
Chinese Journal of Materials Research
基金
国家自然科学基金(51407153)~~
